Tungsten carbonyl derivatives

This type of investigation has recently been extended to chromium and tungsten carbonyl derivatives of sulfur and selenium ligands of this class. ° ... 

In 1980 we published a survey (1) of our major results in this area as of late 1979. These results include extensive work on binuclear CF N PF complexes of cobalt (2,3,4,5) and nickel (6). This paper summarizes our more recent results in this area with particular emphasis on binuclear complexes of chromium, molybdenum, and tungsten as well as some new results on iron carbonyl derivatives. 

Two basic approaches have been taken. The first consists in grafting organometallic donor and acceptor groups, such as ferrocene [as in [84] (Calabrese et al, 1991)] ruthenium derivatives [as in [83] (Whittall et al, 1996)] and tungsten carbonyl, instead of their organic counterparts on tt-conjugated chains. Quite successful in this respect, although not truly org nometallic, are zwitterions based on borate donors and ammonium acceptors [86] (Lambert et ah, 1996) and Lewis acid complexation as in [85] (Kammler et al, 1996). 

The rearrangement of a-acetylenic alcohols into a-p ethylenic carbonyl derivates has been extensively studied. Different catalysts have been proposed acid catalysts such as sulfuric, hydrochloric or acetic acids which give rise to unselective rearrangements [1,2] and more recently, oxo derivatives of vanadium, molybdenum or tungsten in liquid phase [3]. 

Another synthesis of D-oUvose derivative exploited a tungsten carbonyl catalyzed alkynyl alcohol cycloisomerization reaction [54,55]. This useful method allows for synthesis of variety of glycals from an achiral precursor (35), which after enantioselective reduction and Sharpless epoxidation afforded intermediates 39 and 42 (by Mitsunobu inversion), precursors of unnatural D-rhamnal (40) and valuable L-fucal (43) derivatives, respectively (Scheme 4). 

It is apparent that if the Lewis base is charged rather than neutral, the substituted metal carbonyl will have the same charge as the Lewis base. In this manner certain anionic metal carbonyls can be synthesized by the displacement of carbonyl groups with anionic Lewis bases. Frequently used for this type of reaction are the halide ions and cyanide ion. Many of these reactions have been carried out on the relatively stable hexacarbonyls of chromium, molybdenum, and tungsten, their derivatives or other related... 

C. Miscellaneous Chromium, Molybdenum, and Tungsten Carbonyl Anions Other Than Cyclopentadienyl Derivatives... 

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